GRASSY POINT. Grassy Point, on San Antonio Bay and the Refugio-Calhoun county line (at 28°24' N, 96°47' W), is the most southerly point of land at the northern end of San Antonio Bay. It is between Guadalupe and Hynes bays. The point is freshwater marshland composed of mud and sand bottoms in which grow various grasses, rushes, cattails, and slough grass. It is highly flood-prone.